Vitrification of waste materials has previously been accomplished in ceramic lined melting vessels that are capable of being heated to relatively high temperatures such as on the order of about 1500.degree. C. to 1600.degree. C. Such heating as disclosed by U.S. Pat. No. 4,820,328 Roberts et al can be utilized to vitrify waste asbestos by a high temperature melting process. Furthermore, as disclosed by U.S. Pat. No. 5,100,453 Richards such high temperature melting can be utilized to recycle glass fibers such as of the type utilized for building insulation. Likewise, incinerator fly ash can also be vitrified by such high temperature melting in a ceramic melting vessel. During such processing, the waste and any other necessary components to form a glassy material upon heating are introduced into the ceramic melting vessel, and the melted material permeates into seams or any cracks in the ceramic melting vessel sufficiently to cool and thereby seal the vessel so that there is no leakage.
Vitrification of hazardous waste at a lower temperature such as on the order of about 1000.degree. to 1100.degree. C. has also previously been done by heating thereof within a metallic melting vessel. When hazardous waste such as nuclear waste or heavy metals etc. is vitrified, the resultant melted mixture can be delivered into a container for storage upon cooling. However, the metallic melting vessel can fail during use and, in such case, hazardous waste in the melting vessel can contaminate the facility in which the processing is being performed. Such contamination can be a particular problem when nuclear waste processing is involved. Furthermore, heating in a metallic melting vessel has previously been done by passing an electrical current through the melted material between the metallic melting vessel and a stirrer that mixes the material being heated. Thus, the metallic melting vessel and the stirrer act as the electrodes between which the current flows for the heating as mixing takes place. This type of heating is believed to provide superior results due to the direct generation of heat within the melted material by the passage of electric current uniformly through the melt between the stirrer and the melting vessel.